Queens Series Release Notes

Repaired the “synchronous_reader” modifier of enginefacade so that it
refers to the “writer” engine when set to True, thereby allowing
“synchronous” behavior with the writer. When set to False, this is
“asynchronous”, so this should be associated with the async engines.
The flag had the reverse behavior previously.

PyMySQL is a default MySQL DB API driver for oslo.db, as well as for the whole
OpenStack. So far it was possible to use MySQL-python as an alternative DB API driver.
This driver is no longer being tested in this release, hence it should be considered
unsupported. Please switch to PyMySQL, which is an adequate replacement. Refer to
https://wiki.openstack.org/wiki/PyMySQL_evaluation for details.

The configuration option idle_timeout is now deprecated and has been
renamed to connection_recycle_time, including within the main oslo.db
options, as well as in the keyword arguments to
engines.create_engine(), enginefacade.configure() and
enginefacade.configure_defaults(). The new name more accurately
describes what this option does, in that it is not directly related to the
“idle” time of the connection itself, nor is the connection disconnected at
any specific time. It refers to a rule stating that any connection which
has been present more than N seconds as a member of the connection pool
will be automatically discarded and replaced the next time it is checked
out from the pool.